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27503Re: [GrizHFMinimill] Re: boring in steel

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  • trainliker
    Jul 9, 2014
      Oops.  No tailstock in a mill.  And replace the term "headstock" with "mill head".  The rest still applies.
      Chuck K.
      ----- Original Message -----
      Sent: Wednesday, July 09, 2014 2:08 PM
      Subject: Re: [GrizHFMinimill] Re: boring in steel



      Great question.
      It is a way to mitigate the natural bending or "springing" of the cutting tool and/or work piece.
      The idea is to make some final passes without moving the handwheel at all.  Due to the "springiness" that occurred during heavier cutting on the previous pass, another pass will likely cut some more with the same machine setting.
      If possible, it is best to avoid having to do this because it takes more time.  Ways to minimize springiness are to have a stout tool holder and tool, well supported work piece.  Avoid cutting any farther away from the headstock that possible, or put a center in the tailstock to help support the loose end if possible).  Finally, simply learn to plan for it so that you can make a final cut to measure even if some flex, or spring, is present.  And, oh yes, sharp cutting tools make a big difference in avoiding flex.
      Chuck K.
      ----- Original Message -----
      Sent: Wednesday, July 09, 2014 7:10 AM
      Subject: Re: [GrizHFMinimill] Re: boring in steel


      What are spring passes?


      Sent from my iPhone

      On Jul 5, 2014, at 4:41 AM, "joe gifford argie1891@... [GrizHFMinimill]" <GrizHFMinimill@yahoogroups.com> wrote:


      don't forget to make spring passes before you get to final size. I once bored a hole in steel and to smooth out the hole I took several spring passes... wow now my hole was grossly over size. it is hard to believe there is that much spring in a 3/4 inch boring bar made from good quality steel. I have learned a lesson measure while taking spring passes to smooth out the bore. argie1891 aka joe

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